U.S. patent application number 11/087109 was filed with the patent office on 2005-09-29 for the utilization of zirconium and zirconium based alloys for the containment of halogen containing environments used in the production of olefins, alcohols, ethers, and olefin oxides from alkanes.
This patent application is currently assigned to Shell Oil Company. Invention is credited to Hoffpauir, Ronald Anthony, Trevino, Lizbeth Olivia Cisneros.
Application Number | 20050215837 11/087109 |
Document ID | / |
Family ID | 34993315 |
Filed Date | 2005-09-29 |
United States Patent
Application |
20050215837 |
Kind Code |
A1 |
Hoffpauir, Ronald Anthony ;
et al. |
September 29, 2005 |
The utilization of zirconium and zirconium based alloys for the
containment of halogen containing environments used in the
production of olefins, alcohols, ethers, and olefin oxides from
alkanes
Abstract
This invention relates to a process for the production of
olefins, alcohols, ethers, and olefin oxides from alkanes in a
halogen, preferably bromine or chlorine, system, wherein there are
halogenation (reaction of halogen with the alkanes), oxidation
(reaction of alkyl halide with a metal oxide), neutralization
(reaction of hydrogen halide and metal oxide), and regeneration
(reaction of metal halide with air, oxygen, or other oxygen gas
containing mixtures) reactions which take place in the process and
that these reactions, at least, are carried out in reactors made
from metallurgy including zirconium and/or zirconium-based alloys
that contain varying amounts of alloying elements such as tin,
niobium, chromium, iron, oxygen, and nickel. Preferably, this same
metallurgy is used in the fabrication of separation and
purification equipment for the process.
Inventors: |
Hoffpauir, Ronald Anthony;
(Humble, TX) ; Trevino, Lizbeth Olivia Cisneros;
(Stafford, TX) |
Correspondence
Address: |
SHELL OIL COMPANY
P O BOX 2463
HOUSTON
TX
772522463
|
Assignee: |
Shell Oil Company
|
Family ID: |
34993315 |
Appl. No.: |
11/087109 |
Filed: |
March 23, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60555476 |
Mar 23, 2004 |
|
|
|
Current U.S.
Class: |
568/910 |
Current CPC
Class: |
C07C 29/124 20130101;
C07C 41/16 20130101; C07D 301/22 20130101; C07C 1/26 20130101; C07C
17/10 20130101; C07C 29/124 20130101; C07C 41/16 20130101; C07C
31/02 20130101; C07C 31/02 20130101; C07C 43/04 20130101; C07C 1/26
20130101; C07C 11/02 20130101; C07C 29/48 20130101; C07C 29/48
20130101 |
Class at
Publication: |
568/910 |
International
Class: |
C07C 027/16 |
Claims
We claim:
1. A process for the production of olefins, alcohols, ethers, and
olefin oxides from alkanes in a halogen system, wherein there are
halogenation (reaction of halogen with the alkanes), oxidation
(reaction of alkyl halide with a metal oxide), neutralization
(reaction of hydrogen halide and metal oxide), and regeneration
(reaction of metal halide with air, oxygen, or other oxygen gas
containing mixtures) reactions which take place in the process and
that these reactions, at least, are carried out in reactors made
from metallurgy including zirconium and/or zirconium-based alloys
that contain varying amounts of alloying elements such as tin,
niobium, chromium, iron, oxygen, and nickel.
2. The process of claim 1 wherein the zirconium-based alloys may
contain varying amounts, preferably from 0.01 to 3% by weight of
the total weight of the alloy, of alloying elements such as tin,
niobium, chromium, iron, oxygen, and nickel.
3. A process for the production of alcohols, olefins, ethers, and
olefin oxides from alkanes which comprises the steps of: a)
halogenating an alkane to produce a mixture of alkyl halides,
unreacted alkanes, and hydrogen halide; b) oxidizing the alkyl
halide, optionally together with the hydrogen halide, with a metal
oxide to produce the reaction products and metal halide, wherein
the hydrogen halide is optionally separated; c) if the hydrogen
halide is separated in step b), neutralizing it with a metal oxide
to produce a metal halide; and d) regenerating the metal halide(s)
from the oxidation and neutralization steps b) and c) to metal
oxide and halogen using oxygen, air, or a gas mixture containing
oxygen gas such that the halogen and metal oxide may be recycled
for use in the process; wherein these steps are carried out in
equipment which is made from metallurgy which includes zirconium
and/or zirconium based alloys.
4. The process of claim 3 wherein the gas mixture is selected from
the group consisting of blends of oxygen with nitrogen and/or argon
and/or helium.
5. The process of claim 3 wherein the zirconium-based alloys may
contain varying amounts, preferably from 0.01 to 3% by weight of
the total weight of the alloy, of alloying elements such as tin,
niobium, chromium, iron, oxygen, and nickel.
6. The process of claim 3 wherein the metal halides produced in the
oxidation and neutralization reactions are different and they are
regenerated independently.
7. A process for the production of alpha olefins from branched or
n-alkanes of the same carbon number in a halogen system, wherein
there are halogenation (reaction of halogen with the alkanes),
oxidation (reaction of alkyl halide with a metal oxide),
neutralization (reaction of hydrogen halide and metal oxide), and
regeneration (reaction of metal halide with air, oxygen, or other
oxygen gas containing mixtures) reactions which take place in the
process and that these reactions, at least, are carried out in
reactors made from metallurgy including zirconium and/or
zirconium-based alloys that contain varying amounts of alloying
elements such as tin, niobium, chromium, iron, oxygen, and
nickel.
8. The process of claim 7 wherein the zirconium-based alloys may
contain varying amounts, preferably from 0.01 to 3% by weight of
the total weight of the alloy, of alloying elements such as tin,
niobium, chromium, iron, oxygen, and nickel.
9. A process for the production of alpha olefins from branched or
n-alkanes of the same carbon number which comprises the steps of:
a) halogenating linear alkanes, branched alkanes, or a mixture of
linear and branched alkanes to produce a mixture of primary
mono-haloalkanes, internal mono-haloalkanes, unreacted alkanes,
hydrogen halide, and possibly multi-haloalkanes; b) separating the
primary mono-haloalkanes from the mixture of step a) by
distillation or other appropriate separation step(s); c) separating
the hydrogen halide produced in the halogenation step a) and
neutralizing it with a metal oxide or mixture of metal oxides to
produce a partially halogenated metal oxide and/or metal halide or
mixture of partially halogenated metal oxides and/or metal halides
which are then converted for recycle to halogen and metal oxide (or
mixture of metal oxides) using air, oxygen, or gas mixtures
containing oxygen gas; d) oxidizing the separated primary
mono-haloalkane with a metal oxide or combination of metal oxides
to convert the aforesaid primary mono-haloalkane to a mixture of
products that contains alpha olefins, unconverted primary
mono-haloalkanes, and possibly other reaction products, and a
partially halogenated metal oxide and/or metal halide or a mixture
of partially halogenated metal oxides and/or metal halides; e)
separating and regenerating the partially halogenated metal oxide
and/or metal halide or mixture of partially halogenated metal
oxides and/or metal halides from step d) to a metal oxide or
mixture of metal oxides and molecular halogen by reaction with air,
oxygen, or gas mixtures containing oxygen gas wherein the halogen
produced and/or the metal oxide may be recycled; and f) removing
the unreacted primary mono-haloalkane from the reaction mixture and
then purifying the alpha olefin; wherein steps a), c), d), and e)
are carried out in equipment which is made from metallurgy which
includes zirconium and/or zirconium based alloys.
10. The process of claim 9 wherein the gas mixture is selected from
the group consisting of blends of oxygen with nitrogen and/or argon
and/or helium.
11. The process of claim 9 wherein the zirconium-based alloys may
contain varying amounts, preferably from 0.01 to 3% by weight of
the total weight of the alloy, of alloying elements such as tin,
niobium, chromium, iron, oxygen, and nickel.
12. The process of claim 9 wherein the metal halides produced in
the oxidation and neutralization reactions are different and they
are regenerated independently.
13. A process to convert alkanes to primary alcohols of the same
carbon number wherein there are halogenation (reaction of halogen
with the alkanes), oxidation (reaction of alkyl halide with a metal
oxide), and regeneration (reaction of metal halide with air,
oxygen, or other oxygen gas containing mixtures) reactions which
take place in the process and that these reactions, at least, are
carried out in reactors made from metallurgy including zirconium
and/or zirconium-based alloys that contain varying amounts of
alloying elements such as tin, niobium, chromium, iron, oxygen, and
nickel.
14. The process of claim 13 wherein the zirconium-based alloys may
contain varying amounts, preferably from 0.01 to 3% by weight of
the total weight of the alloy, of alloying elements such as tin,
niobium, chromium, iron, oxygen, and nickel.
15. A process for the production of primary alcohols from alkanes
which comprises the steps of: a) halogenating a linear alkane,
branched alkane, or mixture of linear and branched alkanes to
produce a mixture of primary mono-haloalkanes, internal
mono-haloalkanes, unreacted alkanes, hydrogen halide, and possibly
multi-haloalkanes; b) separating the primary mono-haloalkanes from
the mixture of step a) by distillation or other appropriate
separation step(s); c) oxidizing the separated primary
mono-haloalkane with a metal oxide or combination of metal oxides
and water (and possible hydrogen halide) to convert the aforesaid
primary mono-haloalkane to a mixture of products that contains
primary alcohols, unconverted primary mono-haloalkanes, and
possibly other reaction products, and a partially halogenated metal
oxide and/or metal halide or a mixture of partially halogenated
metal oxides and/or metal halides; d) separating and regenerating
the partially halogenated metal oxide and/or metal halide or a
mixture of partially halogenated metal oxides and/or metal halides
to a metal oxide or mixture of metal oxides and molecular halogen
by reaction with air, oxygen or gas mixtures containing oxygen gas,
wherein the halogen produced and/or the metal oxide may be
recycled; and e) removing the unreacted primary mono-haloalkane
from the reaction mixture and then purifying the primary alcohol;
wherein steps a), c) and d) are carried out in equipment which is
made from metallurgy which includes zirconium and/or zirconium
based alloys.
16. The process of claim 15 wherein the zirconium-based alloys may
contain varying amounts, preferably from 0.01 to 3% by weight of
the total weight of the alloy, of alloying elements such as tin,
niobium, chromium, iron, oxygen, and nickel.
17. The process of claim 15 wherein the gas mixture is selected
from the group consisting of blends of oxygen with nitrogen and/or
argon and/or helium.
Description
REFERENCE TO PRIOR APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
application Ser. No. 60/555,476, filed Mar. 23, 2004.
FIELD OF THE INVENTION
[0002] This invention relates to a process for manufacturing
olefins, alcohols, ethers, and olefin oxides from alkanes by mixing
an alkane and halide in the reactor to form alkyl halide and
hydrogen halide wherein the alkyl halide is contacted with a metal
oxide to form an olefin, alcohol, ether, or olefin oxide and metal
halide. More particularly, this invention relates to a choice of
materials for the reactors in which this process is carried
out.
BACKGROUND OF THE INVENTION
[0003] The engineering considerations regarding the industrial
handling of halogen or halogen-containing mixtures are not trivial.
Material of construction identification is critical for the
commercial success of a new process chemistry involving halogens.
For example, in Materials Selection for the Chemical Process
Industries by C. P. Dillon, published by McGraw-Hill Inc. in 1992,
there is a chapter on the production of acetic acid wherein part of
the process involves the carbonylation of methanol and carbon
monoxide in the presence of an iodine-complex catalyst. At page
176, it is stated that zirconium 702 is one of the materials which
could be used in the reactor and flash tank to cope with acetic
acid and iodine compounds at 150.degree. C.
[0004] U.S. Pat. Nos. 4,278,810 and 5,847,203 discuss the problems
with bromine catalyzed reactions for the production of terephthalic
acid. In column 1 of both patents, it is stated that expensive
titanium and titanium alloys have been used as construction
materials in such plants to accommodate the corrosivity of the
bromine systems. Both patents relate to process changes which allow
the use of stainless steel instead of titanium.
[0005] U.S. Pat. No. 4,330,676 describes another such process and
at column 4 states that when the catalyst contains a bromide, a
material must be used for withstanding the resulting highly
corrosive reaction mixture and titanium is given as the
example.
[0006] According to publicly available information (e.g., U.S. Pat.
No. 6,403,840 B1, U.S. Pat. No. 6,462,243 B1, U.S. Pat. No.
6,465,696 B1, U.S. Pat. No. 6,465,699 B1, U.S. Pat. No. 6,472,572
B1, U.S. Pat. No. 6,486,368 B1, and U.S. Pat. No. 6,525,230 B2,
etc., which are herein incorporated by reference), a process exists
which consists of mixing an alkane and a halide in a reactor to
form alkyl halide and hydrogen halide. The isolated alkyl halide or
the alkyl halide and hydrogen halide mixture react with a metal
oxide to produce the products (alcohols, ethers, olefins, or olefin
oxide) and metal halide. The metal halide is oxidized with oxygen
or air to form the original metal oxide and halide, both of which
are recycled.
[0007] The hydrogen halide and/or the alkyl halide, when contacted
with a metal oxide, will likely produce byproducts/products such as
water and hydrogen halide. The combination of these constituents
reacted at temperatures above 100.degree. C. results in an
environment that is highly corrosive to most of the commonly used
metals such as carbon steel, stainless steels, and duplex stainless
steels. This type of environment is especially corrosive in areas
in which a liquid aqueous phase may exist. Some of the more exotic
metals that been proposed for this type of environment (See U.S.
Pat. No. 5,847,203, U.S. Pat. No. 4,330,676, and U.S. Pat. No.
4,278,810) are titanium and Hastelloy C. However, recently
generated test data presented in Example 1 below indicate that
Hastelloy C, or more generically, the nickel-chrome-molybdenum
alloy family, affords very little resistance to corrosion under
conditions which simulated the corrosive conditions that are
anticipated in this process environment.
[0008] According to the documents discussed above, titanium has
been used to overcome the corrosivity of bromine reaction mixtures.
Titanium is a reactive metal and it relies heavily on the integrity
of a protective oxide layer to prevent corrosion damage. Within the
process environment in the present process, there is an inherent
presence of nascent, or unassociated, hydrogen atoms. Nascent
hydrogen is known to penetrate the protective oxide layer and
migrate into the matrix of a base metal. If enough hydrogen
penetrates into the base metal, internal metal hydrides may form
and these are often detrimental to the mechanical properties, as
well as to the metal's ability to resist corrosion. This damage
mechanism is commonly referred to as hydride embrittlement.
[0009] Historically, hydride embrittlement has been recognized as a
problem in many titanium applications. However, the likelihood of
hydride embrittlement of titanium is difficult to precisely
quantify. Controlled laboratory testing of this phenomenon is very
difficult since the onset of hydride formation may take one year or
longer.
SUMMARY OF THE INVENTION
[0010] In one embodiment, the present invention relates to a
process for the production of olefins, alcohols, ethers, and olefin
oxides from alkanes (paraffins) in a halogen, preferably bromine or
chlorine, system, wherein there are halogenation (reaction of
halogen with the alkanes), oxidation (reaction of alkyl halide with
a metal oxide), neutralization (reaction of hydrogen halide and
metal oxide), and regeneration (reaction of metal halide with air,
oxygen, or other oxygen gas containing mixtures) reactions which
take place in the process and that these reactions, at least, are
carried out in reactors made from metallurgy including zirconium
and/or zirconium-based alloys that contain varying amounts of
alloying elements such as tin, niobium, chromium, iron, oxygen, and
nickel. Preferably, this same metallurgy is used in the fabrication
of separation and purification equipment for the process.
[0011] Another embodiment of the present invention describes a
process for the production of alcohols, olefins, ethers, and olefin
oxides from alkanes which comprises the steps of:
[0012] a) halogenating an alkane to produce a mixture of alkyl
halides (mono-haloalkanes and possibly multi-haloalkanes),
unreacted alkanes, and hydrogen halide, preferably wherein the
halogenation step may be carried out thermally and/or
catalytically;
[0013] b) oxidizing the alkyl halide (or a subset of the alkyl
halides such as primary mono-haloalkanes), optionally together with
the hydrogen halide, with a metal oxide to produce the reaction
products and metal halide, wherein the hydrogen halide is
optionally separated;
[0014] c) if the hydrogen halide is separated in step b),
neutralizing it with a metal oxide to produce a metal halide;
and
[0015] d) regenerating the metal halide(s) from the oxidation and
neutralization steps b) and c) to metal oxide and halogen using
oxygen, air, or a gas mixture containing oxygen gas (these mixtures
may include blends of oxygen with nitrogen, argon, or helium) such
that the halogen and metal oxide may be recycled for use in the
process; wherein these steps are carried out in equipment which is
made from metallurgy which includes zirconium and/or zirconium
based alloys. The zirconium-based alloys may contain varying
amounts, preferably from 0.01 to 3% by weight of the total weight
of the alloy, of alloying elements such as tin, niobium, chromium,
iron, oxygen, and nickel. Preferably, other steps of the process
where halogen and water may coexist are also carried out in
equipment made with such metallurgy. Preferably, this same
metallurgy is used in the fabrication of separation and
purification equipment for the process.
[0016] In another embodiment, the invention is a process for the
production of alpha olefins. The process converts branched or
n-alkanes to branched or linear alpha olefins (AO) of the same
carbon number. The halogenation, oxidation, neutralization, and
regeneration reactions, at least, are carried out in reactors made
from the metallurgy described in the preceding embodiment.
[0017] In a further embodiment, the invention is a process for the
conversion of linear, branched or a mixture of linear and branched
alkanes into alpha olefins. It comprises the steps of:
[0018] a) halogenating linear alkanes, branched alkanes, or a
mixture of linear and branched alkane(s) to produce a mixture of
primary mono-haloalkanes (i.e., alkanes with one halogen attached
in the primary position), internal mono-haloalkanes (i.e., alkanes
with one halogen attached somewhere other than the primary
position), unreacted alkanes, hydrogen halide, and possibly
multi-haloalkanes (i.e., alkanes with 2 or more halogens attached),
preferably wherein the halogenation may be carried out thermally or
catalytically;
[0019] b) separating the primary mono-haloalkanes from the mixture
of step a) by distillation or other appropriate separation
step(s);
[0020] c) separating the hydrogen halide produced in the
halogenation step a) and neutralizing it with a metal oxide or
mixture of metal oxides to produce a partially halogenated metal
oxide and/or metal halide or mixture of partially halogenated metal
oxides and/or metal halides which are then converted for recycle to
halogen and metal oxide (or mixture of metal oxides) using air,
oxygen, or gas mixtures containing oxygen gas (these mixtures may
include blends of oxygen with nitrogen, argon, or helium);
[0021] d) oxidizing the separated primary mono-haloalkane with a
metal oxide or combination of metal oxides to convert the aforesaid
primary mono-haloalkane to a mixture of products that contains
alpha olefins, unconverted primary mono-haloalkanes, and possibly
other reaction products (such as internal olefins, primary alcohols
and internal alcohols), and a partially halogenated metal oxide
and/or metal halide or a mixture of partially halogenated metal
oxides and/or metal halides;
[0022] e) separating and regenerating the partially halogenated
metal oxide and/or metal halide or mixture of partially halogenated
metal oxides and/or metal halides from step d) to a metal oxide or
mixture of metal oxides and molecular halogen (such as Cl.sub.2) by
reaction with air, oxygen, or gas mixtures containing oxygen gas
(these mixtures may include blends of oxygen with nitrogen, argon,
or helium) wherein the halogen produced and/or the metal oxide may
be recycled; and
[0023] f) removing the unreacted primary mono-haloalkane from the
reaction mixture and then purifying the alpha olefin; wherein steps
a), c), d), and e) are carried out in equipment which is made from
metallurgy which includes zirconium and/or zirconium based alloys.
The zirconium-based alloys may contain varying amounts, preferably
from 0.01 to 3% by weight of the total weight of the alloy, of
alloying elements such as tin, niobium, chromium, iron, oxygen, and
nickel. Preferably, other steps of the process where halogen and
water may coexist are also carried out in equipment made with such
metallurgy. Preferably, this same metallurgy is used in the
fabrication of separation and purification equipment for the
process.
[0024] In another embodiment, there is described a process to
convert alkanes to primary alcohols of the same carbon number
wherein the halogenation, oxidation, and regeneration, at least,
are carried out in reactors made from metallurgy including
zirconium and zirconium-based alloys that contain varying amounts
of alloying elements such as tin, niobium, chromium, iron, oxygen,
and nickel. Preferably, this same metallurgy is used in the
fabrication of separation and purification equipment for the
process.
[0025] This embodiment describes a process for the production of
primary alcohols from alkanes which comprises the steps of:
[0026] a) halogenating a linear or branched (or mixture of linear
and branched) alkane to produce a mixture of primary
mono-haloalkanes (i.e., alkanes with one halogen attached in the
primary position), internal mono-haloalkanes (i.e., alkanes with
one halogen attached somewhere other than the primary position),
unreacted alkanes, hydrogen halide, and possibly multi-haloalkanes
(i.e., alkanes with 2 or more halogens attached), preferably
wherein the halogenation may be carried out thermally or
catalytically;
[0027] b) separating the primary mono-haloalkanes from the mixture
of step a) by distillation or other appropriate separation
step(s);
[0028] c) oxidizing the separated primary mono-haloalkane with a
metal oxide or combination of metal oxides and water (and possible
hydrogen halide) to convert the aforesaid primary mono-haloalkane
to a mixture of products that contains primary alcohols,
unconverted primary mono-haloalkanes, and possibly other reaction
products (such as internal alcohols and/or olefins), and a
partially halogenated metal oxide and/or metal halide or a mixture
of partially halogenated metal oxides and/or metal halides;
[0029] d) separating and regenerating the partially halogenated
metal oxide and/or metal halide or a mixture of partially
halogenated metal oxides and/or metal halides to a metal oxide or
mixture of metal oxides and molecular halogen (such as Cl.sub.2) by
reaction with air, oxygen or gas mixtures containing oxygen gas
(these mixtures may include blends of oxygen with nitrogen, argon,
or helium), wherein the halogen produced and/or the metal oxide may
be recycled; and
[0030] e) removing the unreacted primary mono-haloalkane from the
reaction mixture and then purifying the primary alcohol; wherein
steps a), c) and d) are carried out in equipment which is made from
metallurgy which includes zirconium and/or zirconium based alloys.
The zirconium-based alloys may contain varying amounts, preferably
from 0.01 to 3% by weight of the total weight of the alloy, of
alloying elements such as tin, niobium, chromium, iron, oxygen, and
nickel. Preferably, other steps of the process where halogen and
water may coexist are also carried out in equipment made with such
metallurgy. Preferably, this same metallurgy is used in the
fabrication of separation and purification equipment for the
process.
DETAILED DESCRIPTION OF THE INVENTION
[0031] The process of the present invention is applicable to the
production of olefins, alcohols, ethers, and olefin oxides from
alkanes of almost any carbon number. The product carbon numbers of
primary interest are C.sub.1 to C.sub.20 and the product carbon
numbers of particular interest are C.sub.8 to C.sub.18.
[0032] Alkanes are converted via halogenation to a mixture of
primary mono-haloalkanes, internal mono-haloalkanes, unreacted
alkanes, hydrogen halide, and possibly multi-haloalkanes.
Halogenation may preferably be carried out thermally or
catalytically (for example in a conventional reactor, in a
catalytic distillation (CD) column, etc.), and with or without the
use of a support intended to promote shape selectivity. For the
production of primary alcohols and alpha olefins, halogenation
processes that preferentially produce primary mono-haloalkanes
(e.g., catalytic halogenation at lower temperatures, thermal
halogenation at higher temperatures, etc.) are preferred. Preferred
halogens are chlorine, bromine, and iodine. For the production of
primary alcohols and alpha olefins, chlorine is preferred. For
other olefins, alcohols, ethers, and olefin oxides, bromine may be
preferred.
[0033] Thermal halogenation is carried out by introducing the
halogen and the alkane to a reactor. The reaction temperature may
be from 100.degree. C. to 400.degree. C. As stated above, catalytic
halogenation may be carried out at lower temperature, such as from
25.degree. C. to 400.degree. C. Catalysts which may be used include
compounds of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co,
Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, B Al, Ga, In, Tl, Si, Ge,
Sn, Pb, P, Sb, Bi, S, Cl, Br, F, Sc, Y, Mg, Ca, Sr, Ba, Na, Li, K,
0, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Er, Yb, Lu and Cs or mixtures
thereof.
[0034] For the case of primary alcohols and alpha olefins, the
mixture of primary mono-haloalkanes, other mono- and
multi-haloalkanes, unreacted alkanes, and hydrogen halide is
transferred to a separation train that isolates the primary
mono-haloalkanes from the mixture. To produce primary alcohols
and/or alpha olefins, it is preferred to direct only primary
mono-haloalkanes to the oxidation reactor. The separation train may
include (1) a distillation or other appropriate separation step to
recover hydrogen halide, (2) a distillation or other appropriate
separation step (or multiple steps) to separate unreacted alkanes,
multi-haloalkanes, and mono-haloalkanes, and (3) an additional
separation step to separate primary mono-haloalkanes from internal
mono-haloalkanes. The unreacted alkanes may be recycled to the
primary halogenation reactor. The multi-haloalkanes may be recycled
to the primary halogenation reactor or may be recycled to a
disproportionation reactor to convert some of the multi-haloalkanes
to mono-haloalkanes. If a disproportionation reactor is used, the
resulting reaction mixture of multi-haloalkanes and
mono-haloalkanes is then recycled to the separation train. The
internal mono-haloalkanes may be recycled to the primary
halogenation reactor or may be recycled to an isomerization reactor
to convert some of the internal mono-haloalkanes to primary
mono-haloalkanes. If an isomerization reactor is used, the
resulting reaction mixture of internal alkyl halides and primary
alkyl halides is then recycled to the separation train.
[0035] Suitable separation schemes include distillation,
adsorption, melt crystallization, and others. For the primary and
internal mono-haloalkanes separation, distillation and melt
crystallization are particularly preferred. For some carbon chain
lengths (C.sub.6-C.sub.10), distillation is preferred because of
differences in boiling points (and as result, relative
volatilities). For other carbon chain lengths (C.sub.12-C.sub.16),
melt crystallization is preferred because of the substantial
freezing point difference between primary and internal
mono-haloalkanes.
[0036] The hydrogen-halide produced in the halogenation reactor may
be separated and neutralized with a metal oxide to produce a metal
halide. Engineering configurations to carry out this hydrogen
halide neutralization process include a single reactor, parallel
reactors, and two reactors (one to trap hydrogen halide and one to
regenerate metal-halide), among others. Using air, oxygen, or other
oxygen gas containing mixtures (these mixtures may include blends
of oxygen with nitrogen, argon, or helium), this metal halide is
converted (regenerated) to halogen and the original metal oxide
both of which are preferably recycled.
[0037] Another option for using the hydrogen halide is to send it
to a metathesis reactor (also called an oxidation reactor), where
alkyl-halides are reacted with metal oxide as explained below.
Metal oxides which may be used in this step and in the other
metathesis reaction below, include oxides of the following metals:
Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ir, Ni,
Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, In, Tl, Si, Ge, Sn, Pb, P,
Sb, Bi, S, Cl, Br, F, Sc, Y, Mg, Ca, Sr, Ba, Na, Li, K, La, Ce, Pr,
Nd, Sm, Eu, Gd, Tb, Er, Yb, Lu, and Cs or mixtures thereof.
[0038] The alkyl-halide (primary mono-haloalkane for the production
of alpha-olefins and/or primary alcohols) that is isolated in the
separation train alone or produced in the halogenation reactor
along with the hydrogen halide is sent into a metathesis reactor
with a selected metal oxide or a combination of metal oxides to
convert the alkyl-halide to a mixture of products. The product
distribution of olefins, alcohols, ethers, and/or olefin oxides
depends on the metal oxide used in the metathesis reaction.
[0039] Water may be fed to the reactor to aid in the formation of
alcohols by providing an extra source of hydrogen and/or oxygen.
The reaction conditions such as residence time, temperature,
reaction phase (solid-gas, solid-liquid, etc.), and addition of
water or hydrogen halide are selected to maximize the desired
product production. The same metal oxide or combination of metal
oxides may be able to produce preferentially different products
(such as alcohols instead of olefins, ethers or olefin oxide)
depending on the reaction conditions. For example, longer residence
times, higher temperatures, and solid-liquid phase reaction tend to
preferentially produce alcohols over olefins. The addition of water
to the metathesis reaction may be crucial for the production of
alcohols.
[0040] The metal oxide or metal oxides used in the metathesis
reactor may or may not be different from the one(s) used in the
neutralization of the hydrogen halide. The metal oxide is partially
(or totally) converted to a metal halide. A purification train is
used to isolate the product. Suitable purification schemes include
distillation, adsorption, melt crystallization, and others. The
unconverted alkyl-halides are recycled to the metathesis
reactor.
[0041] The metal halide is regenerated to metal oxide and halide by
using air, oxygen, or a mixture oxygen gas containing gas (these
mixtures may include blends of oxygen with nitrogen, argon, or
helium). The liberated halogen is preferably recycled to the
halogenation reactor. The regeneration of metal halide to metal
oxide and halide may be accomplished with various reactor
configurations including a separate regeneration reactor, in situ
with a combined regeneration/metathesis reactor where the
air/oxygen flow and primary alkane feed flow are alternated (for
example, as described in U.S. Pat. No. 6,525,230, which is herein
incorporated by reference), in situ regeneration with a multiple
metathesis reactor configuration in a fixed bed mode, etc.
Irrespective of reactor design, type of metal oxide, or halogen,
zirconium metallurgy is suited for the regeneration reactor.
[0042] The final product (olefins, alcohols, ethers or olefins) is
purified in a separation train.
[0043] The present invention offers a family of suitable metals for
the containment of the type of hot wet halogen containing
environments (especially chlorine and bromine) that exist in parts
of this process of reacting alkanes to form olefins, alcohols,
ethers and/or olefin oxides. This invention identifies this
metallurgy as suitable for use in the fabrication of separation
equipment that could be utilized in the purification of
above-mentioned products. The specific metallurgy identified
includes zirconium and zirconium based alloys that contain varying
amounts of alloying elements such as tin, niobium, chromium, iron,
oxygen, and nickel.
[0044] Generally, the alloying elements described above are present
in the zirconium in amounts ranging from 0.01 to 3 percent by
weight of the total alloy. A partial list of these types of
zirconium alloys includes zirconium 702 (aka UNS Grade R60702),
zirconium 704 (aka UNS Grade R60704), zirconium 705 (aka UNS Grade
R60705), zirconium 706 (aka UNS Grade R60706), zirconium 702-S,
Zr-2.5 Nb (aka UNS Grade R60901), Zircaloy-2 (aka UNS Grade
R60802), and Zircaloy-4 (aka UNS Grade R60804).
[0045] The chemical requirements of many of these zirconium based
alloys are provided in the American Standards for Testing and
Materials (ASTM) standard B 551. The chemical composition
requirements for some of these materials expressed in weight
percent (wt %), as provided in ASTM B-551 are as follows: zirconium
702--99.2 minimum wt % Zr+Hf, 0.05 maximum wt % C, 0.2 maximum wt %
F+Cr, 0.005 maximum wt % H, 4.5 maximum wt % Hf, 0.025 maximum wt %
N, and 0.16 maximum wt % oxygen; zirconium 704--97.5 minimum wt %
Zr+Hf, 0.05 maximum wt % C, 0.2-0.4 wt % Fe.sup.+ Cr, 0.005 maximum
wt % H, 4.5 maximum wt % Hf, 0.025 maximum wt % N, 0.18 maximum wt
% oxygen, and 1.0-2.0 wt % Sn; zirconium 705--95.5 minimum wt %
Zr+Hf, 0.05 maximum wt % C, 0.2 maximum wt % Fe+Cr, 0.005 maximum
wt % H, 4.5 maximum wt % Hf, 0.025 maximum wt % N, 2.0-3.0 wt % Nb,
and 0.18 maximum wt % oxygen; and zirconium 706--95.5 wt % Zr+Hf,
0.05 maximum wt % C, 0.2 maximum wt % Fe.sup.+ Cr, 0.005 maximum wt
% H, 4.5 maximum wt % Hf, 0.025 maximum wt % N, 2.0-3.0 wt % Nb,
and 0.16 maximum wt % oxygen.
[0046] Zirconium 702-S is a designator assigned to a recently
developed variation on zirconium 702 that sets a more rigorous
requirement on the amount of Sn that is allowed in the requirements
for zirconium 702. The maximum content of Sn that is allowed in
zirconium 702-S is 0.25 wt % Sn. Otherwise, the chemical
requirements for zirconium 702-S are identical to zirconium 702.
The chemical requirements for this new metal were obtained from a
zirconium manufacturer's website--www.wahchang.com.
[0047] Zircaloy-2 (aka UNS Grade R60802) and Zircaloy-4 (aka UNS
Grade R60802) are both common zirconium-tin (Sn) alloys. The
American Society of Metals (ASM) Handbook, volume 2, provides a
typical composition for these zirconium-tin alloys as follows:
Zircaloy-2--1.4 wt % Sn, 0.1 wt % Fe, 0.1 wt % Cr; 0.05 wt % Ni;
0.12 wt % 0, and the balance Zr; and Zircaloy-4--1.4 wt % Sn, 0.2
wt % Fe, 0.1 wt % Cr, 0.12 wt % 0, and the balance Zr.
[0048] Zr-2.5 Nb (aka UNS Grade R60901) is a common
zirconium-niobium (Nb) alloy. The American Society of Metals (ASM)
Handbook, volume 2, provides a typical composition for this
zirconium-niobium alloy as follows: Zr-2.5Nb--2.6 wt % Nb, 0.14 wt
% 0, and the balance Zr.
[0049] The hydrogen halide and/or the alkyl halide, when contacted
with a metal oxide, may produce byproducts/products such as water
and hydrogen halide. The hot process environment required will
contain water as well as the halogen(s), preferably bromine or
chlorine. The combination of these constituents reacted at
temperatures above 100.degree. C. results in an environment that is
highly corrosive to most of the commonly used metals such as carbon
steel, stainless steels, and duplex stainless steels. The
environment of this process is especially corrosive in areas in
which a liquid aqueous phase may exist. Some of the more exotic
metals that been proposed for this type of environment (See U.S.
Pat. No. 5,847,203, U.S. Pat. No. 4,330,676, and U.S. Pat. No.
4,278,810) are titanium and Hastelloy C. However, recently
generated test data presented in Example 1 indicate that Hastelloy
C, or more generically the nickel-chrome-molybdenum alloy family,
affords very little resistance to corrosion under conditions which
are similar to the corrosive conditions in the environment of this
process. The results from these same tests indicate that zirconium
based metals offer adequate corrosion resistance and are suitable
materials of construction for this processes.
[0050] A comparison of the chemical properties and industrial
experience between titanium and zirconium further supports the
position that zirconium and its alloys are more suitable
alternatives for this process environment. Both of these metals are
classified as reactive metals and they rely heavily on the
integrity of a protective oxide layer to prevent corrosion damage.
Within this process environment there is an inherent presence of
nascent, or unassociated, hydrogen atoms. Nascent hydrogen is known
to penetrate the protective oxide layer and migrate into the matrix
of the base metal. The ability of the zirconium to facilitate the
transport of hydrogen harmlessly through the metal matrix is better
than that of titanium. The solubility of hydrogen in zirconium is
much lower than that of titanium.
[0051] The degree of solubility of hydrogen in the base metals
relates directly to the susceptibility of the base metals to form
internal metal hydrides, which are often detrimental to the
mechanical properties, as well as to the metal's ability to resist
corrosion. This damage mechanism is commonly referred to as hydride
embrittlement.
[0052] Historically hydride embrittlement has been a recognized
problem in many titanium applications. However, the likelihood of
hydride embrittlement of titanium is difficult to precisely
quantify. Controlled laboratory testing of this phenomenon is very
difficult since the onset of hydride formation may take one year or
longer. Consequently, much of the data that relates to hydride
embrittlement of titanium is anecdotally based on field
experiences. However a study of relevant case histories suggests to
us that titanium metal that is exposed to dry, or slightly wet,
highly acidic environments is prone to this form of damage. Based
on this criterion, we consider hydride embrittlement of titanium to
be a significant concern for the present process environment.
[0053] Thus, it appears that titanium should not be chosen as the
metallurgy used in the process of the present invention because of
the significant risk factor. Zirconium, with its ability to
facilitate the transport of hydrogen harmlessly through the metal
matrix and the lower solubility of hydrogen in zirconium, is a much
better choice.
EXAMPLES
[0054] Short term corrosion testing was performed in an attempt to
find acceptable materials for this process environment. These
corrosion tests were conducted in four cells containing water that
was saturated with bromine. Each of the cells were constantly
stirred and maintained at a high enough pressure to ensure the
water remained in the liquid state. The tests were run at two
temperatures, 150.degree. C. and 188.degree. C. These tests
simulated water condensation at those high temperatures.
[0055] Oxygen may have a very dramatic effect on the corrosion
rates of many metals. Since various areas of the proposed process
will have varying contents of oxygen, one set of tests was
initially purged of oxygen by displacement with nitrogen gas, while
the second set allowed for the presence of oxygen
contamination.
[0056] The tests were originally scheduled to run for 10 days. The
thermocouples used to control the temperature of one of the test
cells failed due to corrosion after only three days of operation.
This forced the immediate shut down of this test cell. Upon
inspection of the coupons that were retrieved from this cell it was
determined that the integrity of the remaining test cells, which
were constructed of Hastelloy C276, might have been compromised if
the testing were to continue for the entire 10 day duration. Due to
this concern the tests in the three remaining cells were
subsequently terminated.
[0057] Although the test duration was abbreviated, the corrosion
data reveals a significant advantage in the corrosion resistance of
Zirconium 702 in comparison to the more commonly used nickel and
chrome alloys. The data from these tests are provided in the table
below.
[0058] It should be noted that although this testing targeted a hot
bromine/water environment, similar trends in data are expected for
the analogous chlorine based environment.
1TABLE 1 Corrosion Testing in Hot Aqueous Bromine Environments
Oxygen Inches of Present Test Corrosion Rate Metal Loss Test #
Temperature (Yes/No) Metal Duration (1 mpy = 0.001" per year) per
Year 1 188.degree. C. Yes Type 304L SS 125 hrs 2372 mpy 2.37 2
188.degree. C. Yes Hastelloy B2 125 hrs 443 mpy 0.44 3 188.degree.
C. Yes Hastelloy C276 125 hrs 86 mpy 0.09 4 188.degree. C. Yes
Inconel 625 125 hrs 187 mpy 0.19 5 188.degree. C. Yes Zirconium 702
125 hrs 0.32 mpy 0.0003 6 150.degree. C. Yes Type 304L SS 125 hrs
1397 mpy 1.40 7 150.degree. C. Yes Hastelloy B2 125 hrs 586 mpy
0.59 8 150.degree. C. Yes Hastelloy C276 125 hrs 104 mpy 0.10 9
150.degree. C. Yes Inconel 625 125 hrs 144 mpy 0.14 10 150.degree.
C. Yes Zirconium 702 125 hrs 0.36 mpy 0.0004 11 188.degree. C. No
Type 304L SS 101 hrs 3126 mpy 3.22 12 188.degree. C. No Hastelloy
B2 101 hrs 493 mpy 0.49 13 188.degree. C. No Hastelloy C276 101 hrs
150 mpy 0.15 14 188.degree. C. No Inconel 625 101 hrs 331 mpy 0.33
15 188.degree. C. No Zirconium 702 101 hrs 1.04 mpy 0.001 16
150.degree. C. No Type 304L SS 101 hrs 543 mpy 0.54 17 150.degree.
C. No Hastelloy B2 101 hrs 1160 mpy 1.16 18 150.degree. C. No
Hastelloy C276 101 hrs 38 mpy 0.04 19 150.degree. C. No Inconel 625
101 hrs 81 mpy 0.08 20 150.degree. C. No Zirconium 702 101 hrs 0.54
mpy 0.0005
* * * * *